Semiconductor device

ABSTRACT

The present invention provides a technique for improving the reliability of a semiconductor device where spreading of cracking that occurs at the time of dicing to a seal ring can be restricted even in a semiconductor device with a low-k film used as an interlayer insulating film. Dummy vias are formed in each layer on a dicing region side. The dummy vias are formed at the same intervals in a matrix as viewed in a top view. Even in the case where cracking occurs at the time of dicing, the cracking can be prevented from spreading to a seal ring by the dummy vias. As a result, resistance to moisture absorbed in a circuit formation region can be improved, and deterioration in reliability can be prevented.

CROSS REFERENCE TO RELATED APPLICATIONS

This present application is a continuation application of and claims thebenefit of priority under 35 U.S.C. §120 from application Ser. No.12/107,599, filed Apr. 22, 2008, the entire contents of which isincorporated herein by reference. Application Ser. No. 12/107,599 is acontinuation application of application Ser. No. 11/154,745, filed Jun.17, 2005, now U.S. Pat. No. 7,400,028, which is based on and claims thebenefit of priority under 35 U.S.C. §119 from the prior Japanese PatentApplication No. 2004-182366, filed Jun. 21, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a seal ring which is a protectivestructure for a semiconductor device.

2. Description of the Background Art

A protective structure called a seal ring, a die edge seal or a guardring is provided on an inside of a dicing line, i.e., in the vicinity ofan edge of a chip (die) in order to protect a circuit formation regionof a semiconductor device from influence due to moisture and ions inouter atmosphere. The seal ring is formed of an interconnecting layerand a contact which are the same as those in the circuit formationregion and is formed so as to surround the circuit formation region ofthe semiconductor device.

The circuit formation region of the semiconductor device can beprotected from the influence due to moisture and ions in outeratmosphere by the existence of the seal ring, so that characteristics ofthis semiconductor device can be stabilized for a long period of time.

In addition, the seal ring has the function of suppressing theoccurrence of cracking in the circuit formation region at the time ofdicing in a dicing region. At the time of dicing, cracking may occur inthe dicing region in some cases; however, such cracking can be preventedfrom reaching the circuit formation region by the existence of the sealring between the dicing region and the circuit formation region.

Japanese Patent Application Laid-Open No. 2002-208676 discloses thefollowing technique. A seal ring is formed and a plurality of dummypatterns are provided in a circuit formation region. Then, the flatnessin a chip edge can be improved in a flattening process in accordancewith a CMP (Chemical Mechanical Polishing) method.

In recent years, reduction in resistance of a interconnecting has becomemore important as miniaturization and increase in integration of astructure of a semiconductor device and increase in speed of anoperation have advanced. Accompanying this, Cu (copper) having acomparatively small resistance has become widely used as aninterconnecting material. More specifically, the number of cases wherecopper is utilized in the above-mentioned seal ring structure isincreasing. In addition, a so-called low-k film (k<3.0) having a lowspecific dielectric constant k has become widely used as an interlayerinsulating film.

In the case where such a low-k film is used as an interlayer insulatingfilm, a problem arises where cracking that occurs at the time of dicingeasily exceeds the seal ring and reaches the circuit formation region,so that the circuit formation region is negatively affected. Inaddition, in the case where cracking does not reach the circuitformation region but reaches the seal ring, a problem arises whereresistance to absorbed moisture of the semiconductor devicedeteriorates.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a technique forimproving the reliability of a semiconductor device by preventingcracking that occurs at the time of dicing from reaching a seal ringeven in the case where a low-k film is used as an interlayer insulatingfilm.

According to a first aspect of the present invention, a semiconductordevice includes an interlayer insulating film having a specificdielectric constant of 3 or less, a seal ring formed within theinterlayer insulating film in the vicinity of an edge of a semiconductorchip so as to surround a circuit formation region of the semiconductorchip, and a dummy pattern which is formed within the interlayerinsulating film so as to surround the seal ring in a dicing region ofthe semiconductor chip.

According to the present invention, a dummy pattern is formed so as tosurround a seal ring on a dicing region side of a semiconductor chip.Therefore, even in the case where cracking occurs at the time of dicing,the cracking can be restricted from spreading by the dummy pattern andcan be prevented from reaching the seal ring.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a configuration of a semiconductordevice according to a first embodiment;

FIG. 2 is a top view showing the configuration of the semiconductordevice according to the first embodiment;

FIG. 3 illustrates a manufacturing process for the semiconductor deviceaccording to the first embodiment;

FIG. 4 illustrates a manufacturing process for the semiconductor deviceaccording to the first embodiment;

FIG. 5 illustrates a manufacturing process for the semiconductor deviceaccording to the first embodiment;

FIG. 6 illustrates a manufacturing process for the semiconductor deviceaccording to the first embodiment;

FIG. 7 illustrates a manufacturing process for the semiconductor deviceaccording to the first embodiment;

FIG. 8 illustrates a manufacturing process for the semiconductor deviceaccording to the first embodiment;

FIG. 9 illustrates a manufacturing process for the semiconductor deviceaccording to the first embodiment;

FIG. 10 is a sectional view showing a configuration of a semiconductordevice according to a second embodiment;

FIG. 11 is a top view showing the configuration of the semiconductordevice according to the second embodiment;

FIG. 12 illustrates a manufacturing process for the semiconductor deviceaccording to the second embodiment;

FIG. 13 illustrates a manufacturing process for the semiconductor deviceaccording to the second embodiment;

FIG. 14 illustrates a manufacturing process for the semiconductor deviceaccording to the second embodiment;

FIG. 15 illustrates a manufacturing process for the semiconductor deviceaccording to the second embodiment;

FIG. 16 illustrates a manufacturing process for the semiconductor deviceaccording to the second embodiment;

FIG. 17 illustrates a manufacturing process for the semiconductor deviceaccording to the second embodiment;

FIG. 18 illustrates a manufacturing process for the semiconductor deviceaccording to the second embodiment;

FIG. 19 is a sectional view showing a configuration of a semiconductordevice according to a third embodiment;

FIG. 20 is a top view showing the configuration of the semiconductordevice according to the third embodiment;

FIG. 21 is a sectional view showing a configuration of a semiconductordevice according to a fourth embodiment;

FIG. 22 is a top view showing the configuration of the semiconductordevice according to the fourth embodiment;

FIG. 23 is a sectional view showing a configuration of a semiconductordevice according to a fifth embodiment;

FIG. 24 is a top view showing the configuration of the semiconductordevice according to the fifth embodiment;

FIG. 25 is a sectional view showing a configuration of a semiconductordevice according to a sixth embodiment;

FIG. 26 is a top view showing the configuration of the semiconductordevice according to the sixth embodiment;

FIG. 27 is a sectional view showing a configuration of a semiconductordevice according to a seventh embodiment;

FIG. 28 is a top view showing the configuration of the semiconductordevice according to the seventh embodiment;

FIG. 29 is a sectional view showing a configuration of a semiconductordevice according to an eighth embodiment;

FIG. 30 is a top view showing the configuration of the semiconductordevice according to the eighth embodiment;

FIG. 31 is a sectional view showing a configuration of a semiconductordevice according to a ninth embodiment;

FIG. 32 is a top view showing the configuration of the semiconductordevice according to the ninth embodiment;

FIG. 33 is a sectional view showing a configuration of a semiconductordevice according to a tenth embodiment;

FIG. 34 is a top view showing the configuration of the semiconductordevice according to the tenth embodiment;

FIG. 35 is a sectional view showing a configuration of a semiconductordevice according to an eleventh embodiment;

FIG. 36 is a top view showing the configuration of the semiconductordevice according to the eleventh embodiment;

FIG. 37 is a sectional view showing a configuration of a semiconductordevice according to a twelfth embodiment; and

FIG. 38 is a top view showing the configuration of the semiconductordevice according to the twelfth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIG. 1 shows a configuration of a semiconductor device according to afirst embodiment, which is an enlarged sectional view of a region wherea seal ring is formed.

FIG. 2 is a top view of the semiconductor device viewed along line A1-A1of FIG. 1. In addition, FIG. 1 is also a sectional view taken along lineB1-B1 of FIG. 2. A circuit formation region is to the right and a dicingregion is to the left of the region shown in FIG. 1, respectively.

Here, semiconductor chips are aligned in a matrix on a semiconductorwafer and the respective semiconductor chips are separated by a dicingregion. A circuit formation region is formed in a semiconductor chip anda seal ring is placed around the circuit formation region. Namely, theseal ring is formed to surround the circuit formation region. FIG. 1shows an end surface of such a semiconductor chip and, also, shows thevicinity of an edge (region where a seal ring is formed) of asemiconductor chip.

In the same figure, the circuit portion of the semiconductor device isomitted. In addition, FIG. 1 shows the case of a semiconductor devicewhich is provided with a structure of Cu interconnectings in six layersand Al interconnectings in one layer.

An interlayer insulating film 113 is formed on a silicon substrate 101where a trench isolation (element isolation) film 102 is formed. Thetrench isolation film 102 is formed of, for example, an oxide filmhaving a thickness of 300 nm. The interlayer insulating film 113 isformed of an interlayer insulating film 113 a and a firstinterconnecting insulating film 113 b. Thus, the interlayer insulatingfilm 113 a is formed of, for example, a USG (Undoped Silicon Glass) filmhaving a thickness 500 nm and the first interconnecting insulating film113 b is formed of, for example, a plasma TEOS (Tetraethylorthosilicate) film having a thickness of 300 nm.

A W (tungsten) plug 114 in slit form is formed in the interlayerinsulating film 113 a. In addition, a barrier metal having a structureof TiN (titanium nitride)/Ti (titanium) is formed and W is filled intothe W plug 114. An interconnecting layer 111 is formed on the W plug114. The interconnecting layer 111 is made by burying Cu in a barriermetal having a structure of Ta (tantalum)/TaN (tantalum nitride).

A Cu diffusion prevention insulating film (which may also be referred toas etching stopper film or liner film, and hereinafter simply referredto as diffusion prevention film) 122 is formed on the interlayerinsulating film 113. An interlayer insulating film 123 is formed on thediffusion prevention film 122. In addition, a plurality of dummy vias125 and a slit via 124 in slit form are formed in the interlayerinsulating film 123. The slit via 124 is formed on the interconnectinglayer 111. In addition, the dummy vias 125 are formed on the dicingregion side.

A diffusion prevention film 132 is formed on the interlayer insulatingfilm 123. An interlayer insulating film 133 in which a plurality ofdummy vias 135 and a slit via 134 in slit form are formed is formed onthe diffusion prevention film 132. The slit via 134 is formed on theslit via 124. In addition, the dummy vias 135 are formed on the dummyvias 125.

A diffusion prevention film 142 is formed on the interlayer insulatingfilm 133. An interlayer insulating film 143 in which a plurality ofdummy vias 145 and a slit via 144 in slit form are formed is formed onthe diffusion prevention film 142. The slit via 144 is formed on theslit via 134. In addition, the dummy vias 145 are formed on the dummyvias 135.

A diffusion prevention film 152 is formed on the interlayer insulatingfilm 143. An interlayer insulating film 153 in which a plurality ofdummy vias 155 and a slit via 154 in slit form are formed is formed onthe diffusion prevention film 152. The slit via 154 is formed on theslit via 144. In addition, the dummy vias 155 are formed on the dummyvias 145.

A diffusion prevention film 162 is formed on the interlayer insulatingfilm 153. An interlayer insulating film 163 in which a plurality ofdummy vias 165 and a slit via 164 in slit form are formed is formed onthe diffusion prevention film 162. The slit via 164 is formed to makecontact with the slit via 154. In addition, the dummy vias 165 areformed to make contact with the dummy vias 155.

As shown in FIG. 2, the dummy vias 155 in the fifth layer have adiameter of, for example, 0.14 μm and are aligned at the same intervalsin a matrix with a pitch of, for example, 1 μm. The dummy vias formed inthe second to fourth layers are formed in the same manner. In addition,the dummy vias 165 have a diameter of 0.28 μm and are aligned at thesame intervals in a matrix with a pitch of, for example, 2 μm.

The diffusion prevention films 122, 132, 142, 152 and 162 are formed of,for example, SiC (silicon carbide) films (k to 4.8) having a thicknessof 50 nm. In addition, the interlayer insulating films 123, 133, 143 and153 are formed of SiOC films (carbon-containing silicon oxide films) (kto 2.8) which are low-k films so as to have a film thickness of 500 nm.The interlayer insulating film 163 is formed of a USG film (k to 4.1)having a thickness of approximately 1000 nm.

The slit vias 123, 134, 144, 154 and 164 as well as the dummy vias 125,135, 145, 155 and 165 are made by burying Cu in a barrier metal having astructure of Ta (tantalum)/TaN (tantalum nitride).

A passivation film 173 is formed on the interlayer insulating film 163.The passivation film 173 is formed of, for example, a plasma SiN(silicon nitride) film (k to 7) having a thickness of 500 nm. Inaddition, a hole 174 is formed in the first passivation film 173. Inaddition, an A1 (aluminum) interconnecting layer 171 is formed on thefirst passivation film 173.

The Al interconnecting layer 171 is formed of an Al (aluminum) layeredfilm that contains a barrier metal TiN/Ti film. Thus, the Alinterconnecting layer 171 is formed so as to have a film thickness of1000 nm. A second passivation film 183 is formed so as to cover the Alinterconnecting layer 171. The second passivation film 183 is formed of,for example, a plasma SiN film so as to have a thickness of 1000 nm.

Herein, the W plug 114, the interconnecting layer 111, the slit vias124, 134, 144, 154 and 164 as well as the Al interconnecting layer 171form a seal ring 190.

In addition, the dummy vias 125, 135, 145, 155 and 165 are placed aroundthe seal ring 190. Namely, the dummy vias 125, 135, 145, 155 and 165(dummy pattern) are formed so as to surround the seal ring 190.

FIGS. 3 to 9 illustrate a manufacturing process for the semiconductordevice shown in FIG. 1. In the following, a manufacturing method for asemiconductor device according to this embodiment will be described withreference to these figures.

In the process shown in FIG. 3, a trench isolation film 102 having athickness of, for example, 300 nm is formed in a silicon substrate 101in accordance with an STI (Shallow Trench Isolation) method. Next, anHDP (High Density Plasma) oxide film having a thickness of, for example,800 nm is deposited and 300 nm are polished off in accordance with a CMP(Chemical Mechanical Polishing) method, and thereby, an interlayerinsulating film 113 a is formed. In addition, an opening in slit form isformed in a portion of the interlayer insulating film 113 a thatcorresponds to a seal ring 190 by means of dry etching using a resistmask having a width of, for example, 0.10 μm. At this time, etching iscarried out in a condition where the silicon substrate 101 and theinterlayer insulating film 113 a have a sufficient etching selectionratio.

Subsequently, a barrier metal (not shown) is formed by respectivelydepositing 20 nm of, for example, TiN and Ti in accordance with a CVD(Chemical Vapor Deposition) method, and then, 200 nm of tungsten isdeposited, also in accordance with a CVD method. After that, tungstenand the barrier metal on the interlayer insulating film 113 a areremoved in accordance with a CMP method, and thereby, a W plug 114 inslit form is formed.

Next, a 300 nm plasma TEOS film is deposited on the interlayerinsulating film 113 a so as to form a first interconnecting insulatingfilm 113 b. A resist mask R1 is formed on the first interconnectinginsulating film 113 b, and the plasma TEOS film is etched using theresist mask R1, and thereby, an opening K1 in which an interconnectinglayer 111 is to be formed is formed above the W plug 114 (FIG. 4).

Next, after the resist mask R1 has been removed, 10 nm films of TaN andTa are respectively formed in accordance with a sputtering method, andthereby, a barrier metal (not shown) is formed, and subsequently, 100 nmof Cu is deposited in accordance with a sputtering method so as to forma seed (not shown). Then, 1000 nm of Cu, which is the material for theinterconnecting layer 111, is deposited in accordance with a platingmethod. After this, Cu and the barrier metal on the interlayerinsulating film 113 are removed in accordance with a CMP method, andthereby, the interconnecting layer 111 is formed (FIG. 5).

Next, a 50 nm plasma SiC film is deposited, and thereby, a diffusionprevention film 122 is formed. Subsequently, a 600 nm plasma SiOC film,for example, is deposited and 200 nm is polished off in accordance witha CMP method, and thereby, an interlayer insulating film 123 is formed.After that, the interlayer insulating film 123 is dry etched using aresist mask R2 so as to form openings K2 in which dummy vias 125 and aslit via 124 for forming a seal ring 190 are to be formed (FIG. 6).

At this time, an opening (not shown) in which a second via is formed isformed simultaneously with the openings K2 for the dummy vias 125 andthe slit via 124 in the circuit formation region (not shown).

Next, after an opening (not shown) in which a second interconnectinglayer is formed has been formed in the circuit formation region, 10 nmof Ta and TaN are respectively deposited in accordance with a sputteringmethod. Then, 100 nm of Cu is deposited in accordance with a sputteringmethod so as to form a seed (not shown). After that, 1000 nm of Cu isdeposited in accordance with a plating method, and Cu and the barriermetal on the interlayer insulating film 123 are removed in accordancewith a CMP method. Thus, the dummy vias 125 and the slit via 124 areformed (FIG. 7). In addition, the second via and the secondinterconnecting layer are simultaneously formed in the circuit formationregion.

Next, a 50 nm plasma SiC film is deposited, and thereby, a diffusionprevention film 132 is formed. Subsequently, a 600 nm plasma SiOC film,for example, is deposited and 200 nm is polished off in accordance witha CMP method, and thereby, an interlayer insulating film 133 is formed.After that, the interlayer insulating film 133 is dry etched using aresist mask, and thereby, openings in which dummy vias 135 and a slitvia 134 for forming the seal ring 190 are formed are formed. At thistime, an opening (not shown) in which a third via is formed is formedsimultaneously with the openings for the dummy vias 135 and the slit via134 in the circuit formation region, not shown here.

Next, an opening in which a third interconnecting layer is formed isformed in the circuit formation region. After that, 10 nm of Ta and TaNare respectively deposited in accordance with a sputtering method.

Next, 100 nm of Cu is deposited in accordance with a sputtering method,and thereby, a seed is formed. After that, 1000 nm of Cu is deposited inaccordance with a plating method, and Cu and the barrier metal on theinterlayer insulating film 133 are removed in accordance with a CMPmethod. Thus, the dummy vias 135 and the slit via 134 are formed (FIG.8). In addition, the third via and the third interconnecting layer aresimultaneously formed in the circuit formation region.

Dummy vias 145 and 155, as well as slit vias 144 and 154 in the fourthand fifth layers are formed in accordance with the same procedure. Inaddition, at the same time, fourth and fifth vias, as well as fourth andfifth interconnecting layers are formed in the circuit formation region.The method for formation is the same as that for the second and thirdlayers, and the description thereof is omitted.

Next, in the process shown in FIG. 9, a 50 nm plasma SiC film, forexample, is deposited, and thereby, a diffusion prevention film 162 isformed. Subsequently, a 1200 nm plasma TEOS film, for example, isdeposited and 200 nm is polished off in accordance with a CMP method,and thereby, an interlayer insulating film 163 is formed. After that,dummy vias 165 and a slit via 164 for forming the seal ring 190 areformed in the interlayer insulating film 163. At the same time, a sixthvia and a sixth interconnecting layer are formed in the circuitformation region.

Here, the sixth layer corresponds to the layer where a semi-globalinterconnecting is formed. In addition, in the semi-global process forforming a semi-global interconnecting, semi-global interconnectings arelaid out in dimensions that are, for example, two interconnectings aslarge as those in the process (fine process) for forming localinterconnectings in the first to fifth layers. Therefore, the dummy vias165 are formed so as to have a diameter of 0.28 μm, as shown in FIG. 9,and are laid out in a matrix alignment with a pitch of, for example, 2μm.

Next, a 500 nm plasma SiN film is deposited on the interlayer insulatingfilm 163 so as to form a first passivation film 173. After that, a hole174 is formed in the first passivation film 173. Furthermore, after anAl layered film which includes a barrier metal of TiN/Ti has beendeposited, patterning is carried out so as to form an Al interconnectinglayer 171. Furthermore, a second passivation film 183 is formed after a500 nm plasma SiN film has been deposited. Thus, the structure shown inFIG. 1 can be formed.

As described above, dummy vias are formed on the dicing region side inthe semiconductor device according to this embodiment. Therefore, evenin the case where cracking occurs at the time of dicing, the cracks areprevented from spreading by the dummy vias, and thus, cracking can beprevented from reaching the seal ring 190. Cracking can be preventedfrom reaching the seal ring 190 and the circuit formation region beyondthe seal ring 190, and therefore, resistance to moisture absorbed in thecircuit formation region can be increased, and deterioration inreliability can be prevented.

In addition, in the case where a low-k film is used in a portion wherethe Cu pattern ratio is low, such as a region where a seal ring isformed, the area occupied by the low-k film is increased. Adhesionbetween the low-k film and the diffusion prevention film is not high,and therefore, a problem arises where delamination (peeling of the film)easily occurs.

In this embodiment, the area occupied by the low-k film can be reducedthrough the formation of dummy vias. Therefore, even in the case where alow-k film is used, peeling of the film can be prevented.

Here, though in this embodiment, a case where a plasma SiOC film whichis a low-k film is used as the interlayer insulating film is described,the same effects can be produced with a ULK (Ultra Low-k) film or alayered film having the same.

In addition, though a case is described where the diffusion preventionfilms 122, 132, 142, 152 and 162 are plasma SiC films, they may beplasma SiC films (k: 3 to 4) having a lower dielectric constant, plasmaSiN films or layered films having these. In addition, the same effectscan be produced even in the case where no diffusion prevention film isformed.

Furthermore, though a case is described where the dummy vias and theslit vias are formed of Cu, they may be made of W, TaN, TiN, Ta, Ti orlayered films of these.

Though in this embodiment, a case is described where the dummy vias arevias with a pitch of 1 μm and have a diameter of 0.14 μm, the sameeffects can be produced when the diameter of the vias ranges fromapproximately 1 to 100 times as large as the minimum dimension. Inaddition, the pitch of the vias may be in a range where the occupationratio thereof is from 0.01% to 20%.

Here, minimum dimension means a dimension defined as the diameter ofvias and the width of interconnectings that are designed as vias andinterconnectings formed in the respective layers.

In addition, though the dummy vias are shown to be in square form, theform may be rectangular, as long as it has an opening ratio atapproximately the same level.

Though in this embodiment, a process for forming the dummy viassimultaneously with the vias in the circuit formation region is shown,the dummy vias may be formed before or after the vias in the circuitformation region. Furthermore, they may be formed separately from theslit vias for the seal ring 190. In addition, though a case is describedwhere layers having the same layout are respectively layered, the sameeffects can be produced even in the case where the layout for the upperlayer is shifted by half of the pitch from the layout for the lowerlayer. In addition, the layout in terms of the via diameter and thepitch may be different for each layer.

Second Embodiment

FIG. 10 shows a configuration of a semiconductor device according to asecond embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. FIG. 11 is a top view of the semiconductor deviceas viewed along line A2-A2 of FIG. 10. In addition, FIG. 10 is asectional view of the semiconductor device taken along line B2-B2 ofFIG. 11. In this embodiment, dummy metals and interconnecting layers areadditionally formed in each layer. In the following description, thesame symbols are attached to components that are the same as those inthe first embodiment, and the description thereof is omitted.

A dummy metal 116 is formed in the same plane as an interconnectinglayer 111. In addition, dummy vias 125 are formed on the dummy metal116. A dummy metal 126 is formed on the dummy vias 125. Dummy metals136, 146, 156 and 166 are formed on dummy vias 135, 145, 155 and 165,respectively. In addition, interconnecting layers 121, 131, 141, 151 and161 are formed on slit vias 124, 134, 144, 154 and 164, respectively.

In addition, as shown in FIG. 11, a plurality of dummy metals 156 areplaced parallel to each other so as to cover the top ends of the dummyvias 155. The dummy metals which are formed in other layers are placedin the same manner. Here, the lines of the dummy metals should be formedso as to have a width of no less than 10 μm, in order to prevent dishingthat might occur in a CMP process after the deposition of Cu, and thewidth may be, for example, 2 μm. In addition, the interconnecting layer151 is formed on the slit via 154.

The dummy metals 116, 126, 136, 146, 156 and 166, as well as theinterconnecting layers 111, 121, 131, 141 and 151 are made of a barriermetal having a Ta/TaN structure in which Cu is buried.

Here, the W plug 114, the interconnecting layers 111, 121, 131, 141, 151and 161, the slit vias 124, 134, 144, 154 and 164, as well as an Alinterconnecting layer 171, form a seal ring 190.

In the following, a manufacturing method for the semiconductor deviceaccording to this embodiment will be described with reference to FIGS.12 to 18. First, as described in the first embodiment (FIG. 3), a trenchisolation film 102, an interlayer insulating film 113 and a W plug 114are formed on a silicon substrate 101.

Next, in the process shown in FIG. 12, 300 nm of a plasma TEOS film isdeposited. Then, the plasma TEOS film is etched using a resist mask R1so as to form openings that correspond to the dummy metal 116 and theinterconnecting layer 111.

Subsequently, in the process shown in FIG. 13, a barrier metal (notshown) is formed by respectively forming 10 nm films of TaN and Ta inaccordance with a sputtering method after the resist mask R1 has beenremoved, and then, 100 nm of Cu is deposited in accordance with asputtering method, so as to form a seed (not shown). In addition, 1000nm of Cu, which is the material of the interconnecting layer 111, isdeposited in accordance with a plating method. Then, Cu and the barriermetal on the interlayer insulating film 103 are removed in accordancewith a CMP method, and thereby, the interconnecting layer 111 and thedummy metal 116 are formed.

Next, 50 nm of a plasma SiC film is deposited, and thereby, a diffusionprevention film 122 is formed. Subsequently, 600 nm of a plasma SiOCfilm, for example, is deposited and 200 nm thereof is polished off inaccordance with a CMP method, and thereby, an interlayer insulating film123 is formed. After that, openings K2 in which the dummy vias 125 andthe slit via 124 are to be formed are formed in the interlayerinsulating film 123 through dry etching using a resist mask R2 (FIG.14).

At this time, openings (not shown) in which second vias are to be formedare formed simultaneously with the openings K2 for the dummy vias 125and the slit via 124 in the circuit formation region, not shown here.

Subsequently, in the process shown in FIG. 15, the interlayer insulatingfilm 123 is etched using a resist mask R3, and thereby, openings inwhich the dummy metal 126 and the interconnecting layer 121 are to beformed are formed. At this time, openings (not shown) in which secondinterconnecting layers are to be formed are formed in the circuitformation region, not shown.

Next, in the process shown in FIG. 16, 10 nm of Ta and TaN arerespectively deposited in accordance with a sputtering method after theresist mask R3 has been removed. Then, 100 nm of Cu is deposited inaccordance with a sputtering method, and thereby, a seed is formed (notshown). After that, 1000 nm of Cu is deposited in accordance with aplating method, and Cu and the barrier metal on the interlayerinsulating film 123 are removed in accordance with a CMP method. Thus,the dummy vias 125, the slit via 124, the dummy metals 125 and theinterconnecting layer 121 are simultaneously formed. In addition, thesecond vias and the second interconnecting layers, not shown, aresimultaneously formed in the circuit formation region.

In accordance with the same procedure, dummy vias 135, 145 and 155, slitvias 134, 144 and 154, dummy metals 136, 146 and 156, as well asinterconnecting layers 131, 141 and 151, are formed in the third tofifth layers (FIG. 17). The third to fifth vias and the third to fifthinterconnecting layers are simultaneously formed in the circuitformation region. The formation method is the same as that for thesecond layer, and the description thereof is omitted.

Next, in the process shown in FIG. 18, 50 nm of a plasma SiC film, forexample, is deposited, and thereby, a diffusion prevention film 162 isformed. Subsequently, 1200 nm of a plasma TEOS film, for example, isdeposited and 200 nm thereof is polished off in accordance with a CMPmethod, and thereby, an interlayer insulating film 163 is formed.

Then, in accordance with the same procedure as that in the descriptionsof FIGS. 14 and 15, a slit via 164, dummy vias 165, a dummy metal 166and an interconnecting layer 161 are formed in interlayer insulatingfilm 163. At the same time, sixth vias and sixth interconnecting layersare formed in the circuit formation region.

Herein, the sixth layer corresponds to the layer where semi-globalinterconnectings are formed. In addition, the semi-global process forforming the semi-global interconnectings is designed for a layout ofwhich the dimensions are two times as large as in the process (fineprocess) for forming local interconnectings in the first to fifthlayers. Accordingly, dummy vias 165 are formed so as to have a diameterof 0.28 μm, as shown in FIG. 18, and are laid out in a matrix alignmentwith a pitch of, for example, 2 μm.

Next, a first passivation film 173 is formed by depositing 500 nm of aplasma SiN film on the interlayer insulating film 163. After that, ahole 174 is formed in the first passivation film 173. Furthermore,patterning is carried out so as to form an Al interconnecting layer 171after the deposition of an Al layered film that includes a barrier metalof TiN/Ti. In addition, a second passivation film 183 is formed afterthe deposition of 500 nm of a plasma SiN film. Thus, the structure shownin FIG. 10 can be formed.

In this embodiment, dummy metals are formed in the respective layers.Therefore, cracking that occurs at the time of dicing can further beprevented from spreading. The seal ring 190 can be prevented from beingexposed through cracking and the like, and therefore, moistureabsorption of the circuit formation region can be improved.

In addition, there is a difference in the coefficient of thermalexpansion between the low-k film and the diffusion prevention film.Therefore, there is stress between the low-k film and the diffusionprevention film. In this embodiment, dummy metals are provided, andthereby, the area where the low-k film makes contact with the diffusionprevention film is reduced. As a result, stress between the low-k filmand the diffusion prevention film can be released.

Furthermore, the area where the dummy metals make contact with thediffusion prevention film that has been provided in the upper layer isincreased, as a result of the dummy metals. Adhesion between the dummymetals and the diffusion prevention film is strong, in comparison withthe adhesion between the low-k film and the diffusion prevention film,and therefore, adhesion between the respective layers can be enhanced byincreasing the area of the dummy metals.

In addition, in the case where interconnectings having a large width areused for the dummy metals and the interconnecting layers, a problemarises where the dummy metals and the interconnecting layers may bedisconnected due to dishing during the CMP process after Cu has beenburied.

Furthermore, in the case where interconnectings having a large width areused, a problem arises where voids (SW: Stress Induced Voids) occur injunction portions between dummy vias in an upper layer and dummy metalsin the lower layer (for example, junction portions between the dummyvias 125 and the dummy metal 116) after having been stored at a hightemperature (SM test: Stress Migration test), reducing the reliability.In this embodiment, no interconnectings having a large width are usedfor the dummy metals and the interconnecting layers in the layout, andtherefore, such problems can be prevented.

Third Embodiment

FIG. 19 shows a configuration of a semiconductor device according to athird embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. FIG. 20 is a top view of the semiconductor deviceas viewed along line A3-A3 of FIG. 19. In addition, FIG. 19 is asectional view of the semiconductor device taken along line B3-B3 ofFIG. 20. The same symbols are attached to components that are the sameas those in the first embodiment, and the description thereof isomitted.

In the semiconductor device according to this embodiment, dummy vias 155are arranged in such a manner that they are aligned in zigzag pattern,as shown in the top view of FIG. 20. Namely, dummy vias formed inadjacent columns are shifted by half a pitch from each other. In otherwords, the dummy vias 155 are arranged along a plurality of columns in aplan view, and the dummy vias 155 which are arranged in adjacent columnsare alternately arranged so as to be aligned in zigzag pattern. Thedummy vias that are formed in other layers are aligned in the samemanner. The manufacturing method is the same as that of the firstembodiment, and the description thereof is omitted.

The semiconductor device has the above-mentioned configuration, andtherefore, the same effects are produced as those of the firstembodiment. In addition, in the first embodiment, dummy vias are alignedat the same intervals in a matrix, and therefore, there is a possibilitythat cracking might spread between the dummy vias and reach the sealring. In this embodiment, the dummy vias are arranged in zigzag form asviewed from above, and therefore, the possibility of cracking spreadingbetween the dummy vias becomes low. As a result, spreading of thecracking that occurs at the time of dicing can further be restricted.

Fourth Embodiment

FIG. 21 shows a configuration of a semiconductor device according to afourth embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. The fourth embodiment is gained by combining thesecond and third embodiments, and the same symbols are attached tocomponents that are the same as those in the second and thirdembodiments, and the description thereof is omitted.

FIG. 22 is a top view of the semiconductor device as viewed along lineA4-A4 of FIG. 21, and FIG. 21 is a sectional view of the semiconductordevice taken along line B4-B4 of FIG. 22. As shown in FIG. 22, dummyvias 155 are arranged in such a manner that they are aligned in zigzagpattern. Namely, the dummy vias 155 which are formed in adjacent columnsare shifted by half a pitch from each other. Furthermore, a dummy metal156 is formed over the dummy vias 155. Other layers are formed in thesame manner. In addition, the manufacturing method is the same as thatof the second embodiment, and the description thereof is omitted.

As described above, in this embodiment, dummy vias are arranged inzigzag form, and a dummy metal is formed in each layer. In addition, thedummy metal is placed so as to cover the dummy vias. As a result,spreading of the cracking that occurs at the time of dicing can furtherbe restricted. In addition, the formation of the dummy metals relievesstress between the low-k films and the diffusion prevention films, andadhesion between these films can be enhanced.

Fifth Embodiment

FIG. 23 shows a configuration of a semiconductor device according to afifth embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. FIG. 24 is a top view of the semiconductor deviceas viewed along line A5-A5 of FIG. 23, and FIG. 23 is a sectional viewof the semiconductor device taken along line B5-B5 of FIG. 24.

In this embodiment, as shown in FIG. 24, dummy slit vias 557 are formedinstead of the dummy vias 155. The dummy slit vias 557, in their minimumdimensions, are formed so as to have a slit width of, for example, 0.14μm. Each of the second to fourth layers has the same configuration, anddummy slit vias 527, 537 and 547 are formed. Dummy slit vias 567 in thesixth layer are formed so as to have a slit width of 0.28 μm.

The other parts of the configuration are the same as those in the firstembodiment and the same symbols are attached to components that are thesame, and the description thereof is omitted. The manufacturing methodis the same as that of the first embodiment, except that dummy slit viasare formed instead of dummy vias, and the description thereof isomitted.

As described above, dummy slit vias are formed instead of dummy vias onthe dicing region side according to this embodiment. Dummy slit vias areformed on the dicing region side, and thereby, spreading of crackingthat occurs at the time of dicing can be restricted more efficientlythan the case where dummy vias are formed. Spreading of cracking to theseal ring 190 can be prevented by placing dummy slits, and therefore,resistance to moisture absorbed in the circuit formation region can beincreased.

Furthermore, the dummy slit vias which have the structure in slit formcan reduce the area occupied by the low-k film, in comparison with thedummy vias. Therefore, stress between the low-k film and the diffusionprevention film can be relieved.

In addition, the area where the low-k film and the diffusion preventionfilm make contact with each other is reduced by providing the dummy slitvias, and therefore, adhesion between these films can be enhanced.

Sixth Embodiment

FIG. 25 shows a configuration of a semiconductor device according to asixth embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. FIG. 26 is a top view of the semiconductor deviceas viewed along line A6-A6 of FIG. 25, and FIG. 25 is a sectional viewof the semiconductor device taken along line B6-B6 of FIG. 26.

The sixth embodiment is gained by combining the second and fifthembodiments, and the same symbols are attached to components that arethe same as those in the second and fifth embodiments, and thedescription thereof is omitted.

In this embodiment, dummy metals are further formed in each layer of thefirst to sixth layers, in addition to the dummy slit vias.

As shown in FIG. 26, dummy metals 156 which are formed in, for example,the fifth layer, are formed at the same intervals, so as to cross overdummy slit vias 557 at right angles. Dummy slit vias 527, 537, 547 and567, as well as dummy metals 126, 136, 146, 156 and 166, are formed inthe second to fourth layers and sixth layer in the same manner. In thefirst layer, only dummy metals 116 are formed.

Here, the manufacturing method is the same as the manufacturing methodshown in the second embodiment, and therefore, the detailed descriptionthereof is omitted.

Dummy metals are formed over dummy slits, and thereby, spreading ofcracking that occurs at the time of dicing can be efficientlyrestricted, in comparison with a configuration which has only dummy slitvias.

In addition, dummy metals are formed in addition to dummy slit vias, andthereby, the area occupied by the low-k film is reduced, so that stressbetween the low-k film and the diffusion prevention film can berelieved, and adhesion between these films can be enhanced.

Seventh Embodiment

FIG. 27 shows a configuration of a semiconductor device according to aseventh embodiment, which is an enlarged sectional view of a regionwhere a seal ring is formed. FIG. 28 is a top view of the semiconductordevice as viewed along line A7-A7 of FIG. 27, and FIG. 27 is a sectionalview of the semiconductor device taken along line B7-B7 of FIG. 28.

In this embodiment, as shown in FIG. 28, dummy slit vias 557 are formedso as to have thick line widths. The other parts of the configurationare the same as those in the fifth embodiment, and the same symbols areattached to components that are the same, and the description thereof isomitted.

The dummy slit vias are formed so as to have a line width of, forexample, 1 μm. Dummy slit vias 527, 537 and 547 are formed in the secondto fourth layers so as to have the same thick line width. In the sixthlayer, dummy slit vias 567 are formed so as to have a line width of, forexample, 2 μm.

Here, the manufacturing method is the same as the manufacturing methodshown in the first embodiment, except that dummy slit vias are formedinstead of dummy vias, and the description thereof is omitted.

As described above, a thick width dummy slit via structure where theline widths have been increased is used, and thereby, spreading ofcracking that occurs at the time of dicing can be efficientlyrestricted, in comparison with the case where the line width is small.

In addition, the area occupied by the low-k film is reduced by formingdummy slit vias with a great width. Therefore, stress between the low-kfilm and the diffusion prevention film can be relieved.

Furthermore, the area where the dummy slit vias and the diffusionprevention film that is formed in the upper layer make contact with eachother becomes great, in comparison with the case where dummy slit viashaving a small width are used, and therefore, adhesion between the dummyslit vias and the diffusion prevention film can be enhanced.

Here, the line width of the dummy slit vias is not limited to 1 μm, andthe same effects can be produced in the case where the line width is 0.8μm to 2 μm. In general, the same effects can be produced in the casewhere the dummy slit vias are formed so as to have a line width that is5 to 20 times greater than the minimum dimensions that are defined bythe diameter of vias or the width of interconnectings for designing viasand interconnectings that are formed in each layer. However, it isnecessary to optimize the conditions for the manufacturing process, forexample, the etching conditions and the film thickness of Cu plating forfilling in dummy slit vias, on the basis of the line width.

Eighth Embodiment

FIG. 29 shows a configuration of a semiconductor device according to aneighth embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. FIG. 30 is a top view of the semiconductor devicealong line A8-A8 of FIG. 29 and FIG. 29 is a sectional view of thesemiconductor device taken along line B8-B8 of FIG. 30.

This embodiment is gained by thickening the line width of the dummy slitvias in the sixth embodiment. The dummy slit vias are formed so as tohave a line width of, for example, 1 μm. The other parts of theconfiguration are the same as those in the sixth embodiment, and thesame symbols are attached to the same components and the descriptionthereof is omitted.

As described above, dummy metals are formed in the respective layers,and in addition, a thick width dummy slit via structure having a thickline width is used, and thereby, spreading of cracking that occurs atthe time of dicing can be efficiently restricted in comparison with thecase where the line width is thin.

In addition, the area occupied the low-k film is reduced, and thereby,stress between the low-k film and the diffusion prevention film can berelieved.

Furthermore, the area where the low-k film and the diffusion preventionfilm make contact with each other becomes smaller than in the case wheredummy slit vias having a smaller line width are formed, and therefore,adhesion between these films can be increased.

Here, the line width of the dummy slit vias is not limited to 1 μm, butrather the same effects can be produced in the case where the line widthis 0.8 μm to 2 μm. In general, the same effects can be produced in thecase where the dummy slit vias have a line width 5 to 20 times greaterthan the minimum dimensions that are defined by the diameter of vias orthe width of interconnectings for designing vias and interconnectingsthat are formed in each layer. However, it is necessary to optimize theconditions for the manufacturing process, for example, the etchingconditions and the film thickness of Cu plating for filling in dummyslit vias, on the basis of the line width.

Ninth Embodiment

FIG. 31 shows a configuration of a semiconductor device according to aninth embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. FIG. 32 is a sectional view of the semiconductordevice taken along line A9-A9 of FIG. 31 and FIG. 31 is a sectional viewof the semiconductor device taken along line B9-B9 of FIG. 32.

The ninth embodiment is gained by combining the first and fifthembodiments, and the same symbols are attached to the same components asthe first and fifth embodiments and the description thereof is omitted.

In this embodiment, dummy vias and dummy slit vias are formed in therespective layers from the second to sixth layers on the dicing regionside.

As shown in FIG. 32, dummy vias 155 are formed at the same intervals ina matrix on both sides of a dummy slit via 557. The other layers havethe same structure.

In the above-mentioned structure, spreading of cracking can be preventedby the dummy slit via even in the case where cracking that occurs at thetime of dicing spreads between the dummy vias. Therefore, spreading ofcracking can be reduced in comparison with the structure shown in thefirst embodiment.

In addition, a structure where dummy vias and a dummy slit via arecombined is provided, and therefore, the area occupied by the low-k filmcan be reduced in comparison with the structure of the first embodimentthat is provided with only dummy vias. Therefore, stress between thelow-k film and the diffusion prevention film can be relieved.

Furthermore, the area where the low-k film and the diffusion preventionfilm make contact with each other is reduced and adhesion between thesefilms can be increased.

Tenth Embodiment

FIG. 33 shows a configuration of a semiconductor device according to atenth embodiment, which is an enlarged sectional view of a region wherea seal ring is formed. FIG. 34 is a top view of the semiconductor deviceas viewed along line A10-A10 of FIG. 33 and FIG. 33 is a sectional viewof the semiconductor device taken along line B10-B10 of FIG. 34.

The tenth embodiment is gained by combining the second and ninthembodiments, and the same symbols are attached to the same components asthose in the second and ninth embodiments and the description thereof isomitted.

As shown is FIG. 33, dummy slit vias and dummy vias are formed on thedicing region side and dummy metals are formed in the respective layersfrom the first to sixth layers. In addition, as shown in FIG. 34, dummyvias 155 are formed at the same intervals in a matrix on both sides of adummy slit via 557. In addition, a dummy metal 156 is formed so as tocover the dummy slit via 557 and the dummy vias 155. The second tofourth and sixth layers are respectively formed in the same manner.

Here, the manufacturing method is almost the same as that of the secondembodiment and the description thereof is omitted.

Dummy metals are formed in the respective layers so as to cover thedummy slit vias and the dummy vias, and thereby, spreading of crackingthat occurs at the time of dicing can further be restricted incomparison with the structure of the ninth embodiment.

In addition, the area where the low-k film makes contact with thediffusion prevention film is reduced by providing a dummy metal. As aresult, stress between the low-k film and the diffusion prevention filmcan be relieved. Furthermore, adhesion between the respective layers canbe enhanced.

Eleventh Embodiment

FIG. 35 shows a configuration of a semiconductor device according to aneleventh embodiment, which is an enlarged sectional view of a regionwhere a seal ring is formed. FIG. 36 is a top view of the semiconductordevice as viewed along line A11-A11 of FIG. 35, and FIG. 35 is asectional view of the semiconductor device taken along line B11-B11 ofFIG. 36.

In this embodiment, as shown in FIG. 36, dummy vias 155 are formed onboth sides of a dummy slit via 557. In addition, dummy vias 155 arearranged in a zigzag manner. The other layers have the sameconfiguration.

The other parts of the configuration are the same as those in the ninthembodiment, and the same symbols are attached to the same components andthe description thereof is omitted. In addition, the manufacturingmethod is the same as the manufacturing method described in the firstembodiment and the description thereof is omitted.

In this embodiment, dummy vias are arranged in a zigzag manner, andthereby, the amount of cracking that reaches the dummy slit via can bereduced. In addition, even in the case where cracking spreads beyond thedummy slit via, the amount of cracking that reaches the seal ring 190can be reduced in comparison with the configuration of the ninthembodiment due to the additional formation of dummy vias which arearranged in a zigzag manner between the dummy slit and the seal ring190.

Twelfth Embodiment

FIG. 37 shows a configuration of a semiconductor device according to atwelfth embodiment, which is an enlarged sectional view of a regionwhere a seal ring is formed. The twelfth embodiment is gained bycombining the second and eleventh embodiments, and the same symbols areattached to the same components as those in the second and eleventhembodiments and the description thereof is omitted.

Here, the manufacturing method is the same as the manufacturing methoddescribed in the second embodiment, and therefore, the descriptionthereof is omitted.

FIG. 38 is a top view of the fifth layer. As shown in FIG. 38, a dummymetal 156 is formed so as to cover a dummy slit via 557 and dummy vias155. In addition, the second to fourth and sixth layers are respectivelyformed in the same manner. Only dummy metals 116 are formed in the firstlayer.

In this embodiment, dummy metals are formed so as to cover the dummyslit vias and the dummy vias. Therefore, spreading of cracking thatoccurs at the time of dicing can further be restricted in comparisonwith the structure of the eleventh embodiment.

Furthermore, the area where the low-k film makes contact with thediffusion prevention film is reduced by providing dummy metals. As aresult, stress between the low-k film and the diffusion prevention filmcan be relieved. In addition, adhesion between the respective layers canbe enhanced.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

What is claimed is:
 1. A semiconductor device comprising: a firstinsulating layer which has a specific dielectric constant of 3 or less;a first dummy metal which is formed in the first insulating layer; asecond insulating layer which is formed on a surface of the firstinsulating layer and the first dummy metal; a third insulating layerwhich is formed on the second insulating layer, and which has a specificdielectric constant of 3 or less; a second dummy metal which is formedin the third insulating layer; a fourth insulating layer which is formedon a surface of the third insulating layer and the second dummy metal; aplurality of dummy vias which make plural interconnections between asurface of the first dummy metal and a bottom of the second dummy metal;and a seal which is formed through the first insulating layer, thesecond insulating layer and the third insulating layer so as to surrounda circuit formation region of the semiconductor device, wherein thefirst dummy metal, the second dummy metal and the dummy vias are formedin a region which is outside the seal, in a direction towards an edge ofthe semiconductor device and away from the seal, each of the seal, thefirst dummy metal, the second dummy metal and the dummy vias includes Cumaterial, and the dummy vias are arranged along a plurality of columnsin plan view in such a manner that the dummy vias form a zigzagarrangement in which the dummy vias that are arranged in adjacentcolumns are not aligned with one another in a spacing direction whilethe dummy vias in columns spaced apart from each other by one adjacentcolumn are aligned with one another in the spacing direction.
 2. Thesemiconductor device according to claim 1, wherein: each of the secondinsulating layer and the fourth insulating layer includes a filmselected from a SiN film and a SiC film, the seal is formed in avicinity of an edge of the semiconductor device, and a dicing region isarranged outside the seal.
 3. The semiconductor device according toclaim 2, further comprising: dummy slit vias surrounding the seal, witha first dummy slit via formed in the first insulating layer and a seconddummy slit via formed in the third insulating layer.
 4. Thesemiconductor device according to claim 3, wherein: a line width of thedummy slit via is 5 to 20 times greater than a minimum dimension, andthe minimum dimension is a dimension defined as a diameter of vias and awidth of interconnections that are designed as vias and interconnectionsformed in respective layers.
 5. The semiconductor device according toclaim 1, wherein: a diameter of the dummy vias is 1 to 20 times greaterthan a minimum dimension, and the minimum dimension is a dimensiondefined as a diameter of vias and a width of interconnections that aredesigned as vias and interconnections formed in respective layers.